LVM operations

create LV

1. create disk partition (fdisk)
2. pvcreate /dev/sdb1
3. lvmdiskscan , pvdisplay , pvscan(to check)
4. vgcreate vg_newlvm /dev/sdb1
   vgcreate vg_newlvm /dev/sdb1 /dev/sdc1 
5. lvcreate --name centos7_newvol -l 100%FREE vg_newlvm
   lvcreate -L 15G vg_newlvm
   lvcreate -l 50%VG -n centos7_newvol vg_newlvm
6. lvdisplay (to check)
7. mkfs.ext4 /dev/vg_newlvm/centos7_newvol

resize LV

1. Identify the Volume Group
   vgs
2. Extend the Volume Group
   vgextend myvolume /dev/sda2
3. Check
   vgs , vgdisplay
4. Extend the Logical Volume
   lvextend -l +100%FREE /dev/myvg/myvolume
Note: You can also extend the file system size using single lvextnd command by adding -r at end, example is shown below
   lvextend -l +100%FREE /dev/myvg/myvolume -r
5. Extend the filesystem
   xfs_growfs /dev/myvg/myvolume

disable/delete LV

1. Delete the entry of the mount point from the /etc/fstab :
# cat /etc/fstab
...
/dev/mapper/datavg-testlv            /data01              ext4    defaults        0 0
...
2. Unmount the mount point : 
# umount /data01

3. Disable lvm :
# lvchange -an /dev/datavg/testlv

4. Delete lvm volume :
# lvremove /dev/datavg/testlv

5. Disable volume group :
# vgchange -an datavg

6. Delete volume group :
# vgremove datavg

7. Delete physical Volumes being used for the volume group “datavg” :
# pvremove /dev/sdb  /dev/sdc

mount LVM from external disk

Make sure lvm2 is installed:

$ sudo yum install lvm2
Load the necessary module(s) as root:

$ sudo modprobe dm-mod
Scan your system for LVM volumes and identify in the output the volume group name that has your Fedora volume (mine proved to be VolGroup00):

$ sudo vgscan
Activate the volume:

$ sudo vgchange -ay VolGroup00
Find the logical volume that has your Fedora root filesystem (mine proved to be LogVol00):

$ sudo lvs
Create a mount point for that volume:

$ sudo mkdir /mnt/fcroot
Mount it:

$ sudo mount /dev/VolGroup00/LogVol00 /mnt/fcroot -o ro,user
You're done, navigate to /mnt/fcroot and copy the files and paste somewhere else.

Note: In case of bad sectors on the disk, one can prevent journaling with the option noload.